In this study, the techniques of migrating legacy software systems into web service-based architecture has been discussed. This procedure is carried out based on the fact that software and business companies want to migrate along with previous systems, to a more recent technology, which are of higher benefit to both businesses and their client. With the above issue in mind, this study executed a systematic literature review to look into the various techniques that were existing in published literatures or articles and come up with a comprehensive summary that highlighted their strength and weaknesses for future improvement.